Engine starter control system



Feb. 2, 1954 B. H. SHORT ETAL 2,668,247

ENGINE STARTER CONTROL SYSTEM Original Filed Oct. 30, 1946 davmzroezm 400 600 800' M00 /200' M00 x00 aw 3. I4 7 I2 5 7 A5 5557 v INVENTORS 7 56 5127016 bfifiorzQJa/En Wla'eru '1- BY y 4 My 9 Patented Feb. 2, 1954 2,668,247 ENGINE STARTER CONTROL SYSTEM Brooks H. Short, Anderson, Pendleton, Ind., assignors and John W. Dyer, to General Motors Corporation, Detroit, Mich, a corporation of Delaware Driginal application Octob Divided and 1951, Serial No. 229,963

2 Claims. (01. 29036) This invention relates to engine starter control systems and aims to prevent use of the starter while the engine is running.

The object of the invention is accomplished by the use of a relay switch which at the maximum cranking speed maintains its contacts closed so that the starting motor can be operated in the usual manner by a starter switch. The electromagnet of the relay is responsive to the voltage of the generator which, below the cut-in speed when the cutout relay is open, is separately excited from the battery and is self-excited when the cutout relay closes. By such arrangement, the relay switch will separate its contacts in the starter control circuit at a speed above the maxi mum cranking speed of the engine and well below the cut-in speed so that the cranking is discontinued automatically before engine speed increases very much above the maximum cranking speed after the engine becomes self-operative. This is of advantage to the engine starter because the starting motor pinion is automatically disengaged from the engine flywheel gear at a speed considerably lower than the minimum sustaining speed of the engine. the relay switch holds its contacts open until the engine speed falls to practically zero. This re sult is obtained because below engine cut-in speed, the generator changes from self-exciting status to separately exciting status whereby its voltage output below cut-in speed is very much higher than it would be if the generator were self-excited below cut-in speed. Consequently, the relay holds its contacts open until generator speed practically is zero.

Further objects and; advantages of the present invention will be apparent from the following description, reference being had to the accompanying drawings, wherein preferred embodiments of the present invention are clearly shown.

In the drawings:

Figs. 1 and 2 are examples of wiring diagrams embodying the invention.

Fig. 3 is a chart for illustrating the operation of the generator when self-excited and when separately-excited.

Fig. 4 is a wiring diagram showing, in detail, one of the units of the other diagrams.

Referring to Fig. 1, a generator driven by terminal grounded and the terminal [5. One erator is and the Another advantage is that or 30, 1946, Serial No.

this application June 5,

:3 Ave Terminal it of unit !5 is connected with wire H. A switch It connects wire I? with Wire 19 connected with the ignition apparatus as well as field coil l3.

Wire I! is connected. 'witi'i the battery which is grounded and with a contact as of a main starter switch, designated generally by numeral 35, having another fixed contact 39 which is connected with a starting motor 49 which is grounded and has its field coil ll connected by wire 2 with said contact 39. A movable contact 31 is adapted to engage the contacts 3-3 and 39 to cause operation of the starting motor and this contact is carried by an armature 36 of an electromagnet which is controlled in a manner to be described, to control the operation of said starting motor.

Unit i 5, shown in detail in Fig. 4, is a combined voltage regulator, current regulator and cutout relay. The cutout relay 5!! comprises an armature 5! attached to a spring blade 52 carrying 'a contact 53 adapted to engage a contact 54 connected with the terminal IS. The relay includes a core 55 carrying a fine winding 56 which is grounded and carrying a coarse winding iii connected at one end to blade 52.

Current regulator 66 has a coil 5! connected at one end with winding 57 of relay 58 and at the other end with the terminal 12. Coil 6i surrounds a core 62 facing an armature 63 carried by a spring blade 64 carrying a contact 65 normally engaging a contact 65 connected with a wire 61.

The voltage regulator it comprises a core H surrounded by a coil l2 connected at one end with wire 61 and at the other end with terminal 14 and with a wire 13 connected with a resistance 14 which is grounded and with a resistance 15 which is connected with wire it which connects blade 6d of regulator 59 with a contact 77 normally engaged by a contact :3 carried by a spring blade 19 which is grounded and which carries an armature 89 facing the core H. Core ii is surrounded also by a coil 8| which is grounded at one end and which is connected at the other end with wire 82 connected with the cutout relay windings E39 and 56 and with the spring blade 52.

As shown in Fig. l, the wire IQ is connected to the fixed contact 2| or a manually operated switch, designated generally as 25, which is closed by the operator when it is desired to start the engine. This switch has a second fixed contact 23 and a manually operable contact 22 normally held out of engagement with the fixed contacts by a spring 24 and movable into engagement therewith by the operator. The connected by a wire to the fixed contact 28 of a fixed contact 23 is normally closed relay switch 353, which has a movable contact 2? carried by an armature 26 of a magnet having a winding 3| and a core 32, the winding being grounded as indicated and connected to the armature 26, so that when the switch 25 is closed, current is caused to flow through the winding 3 I As already stated, the movable contact 31 of the main starter switch 35 is carried by the armature 38. This magnet has two coils 33 and 34 which, when energized, eiiect movement of the contact 3! into engagement with fixed contacts 33 and 39 against the force of a spring 36a which normally holds the switch open. Both coils are effective to move the armature 36 to close said switch, but as soon as the switch is closed, the coil 34 is short circuited so that the switch is held closed only by the coil 33 during the cranking of the engine to effect starting.

Energization of coils 33 and 34 is controlled by a normally open relay switch designated generally by the numeral which has a fixed contact 95 connected with the wire l! leading from the battery and a movable contact 93 carried by an armature 96, connected by a wire 96 with the coils 34 and 35. This relay switch includes a winding 9i surrounding a core 56 and in series with the winding iii and armature 26 of the switch 30. When current flows through winding 9|, the contacts 93 and 95 are engaged and current flows from the battery through such contacts and wire 96 to the coils 33 and 34 to efiect closing of the circuit between the battery and the starting motor 49.

To start the engine, the ignition is turned on by closing switch 3. Current then flows from the battery 28 to the ignition apparatus through wire ll, switch l8 and wire :9 and also to the generator field I3 and out through the terminal l4 and to ground through coil 12 of regulator Til, wire 61, contacts GI, 65 of the regulator 60, blade 64, wire 16, contacts 77 and i8 of regulator 18 and armature 79 which is grounded. The switch 25 is then closed which causes current to flow from the battery through wire [9, switch 25, and the wire leading from contact 25 through winding 9! and winding 3% to ground. The current flowing through winding 9| efiects engagement of contacts 93 and 25 so that current flows from the battery through wire H, the contacts 93, 95, armature a l and wire 96 to the coils 33 and 3 to effect movement of contact 3'! into engagement with contacts 38 and 3-9 so as to close the main switch 35. As already stated, when this takes place the coil 34 is short circuited and the magnet remains in circuit closing status solely by reason of the energization of coil 33, which exerts sufficient force to hold the switch 35 closed during the cranking operation.

' The closing of the switch 25 to cause cranking of the engine places the winding 9| and winding 3| in series with the battery after the ignition switch 18 is closed. At a generator speed slightly above maximum cranking speed the excitation of coil 3! of relay switch 30 is increased sufliciently to cause opening of the contacts 2i and 23. This results in de-energization of winding ill of relay switch iii) and operation of the starting motor 48 ceases. In case the relay switch 3 fails to open, relay switch EH3 will open when the generator cuts in because coil ai is then short circuited by reason of the connection II. This short circuit is established through conductor Ii, terminal i2, current coil 6|, current coil 57, blade 52, contacts 53 and 54,

which are closed when the generator cuts in by operation of voltage coil 56, terminal I6, ignition switch !8, wire I9 and switches and 28. With the arrangement shown, the relay switches 32 and 9t provide double protection.

During the cranking of the engine, the generator operates as a separatively-excited generator and produces an output represented by the line A-B (Fig. 3). The battery supplies current to the field at 5.5 volts, for example, if the battery is fairly well charged. Below maximum cranking speed, about 300 R. P. M. generator speed or 150 R. P. M. engine speed, the maximum voltage output of the generator is below two volts which is insufficient to cause relay to separate its contacts 2'? and 2B. Relay 30 is constructed so as to separate its contacts at 2.25 volts and to close its contacts when the voltage impressed on its coil is 1.2 volts. Therefore, when the engine becomes self-operative, the generator output when self-excited, will reach 2.25 volts at about 360 R. P. M. generator speed or 180 R. P. M. engine speed. Therefore, long before the speed of the engine can rise to cut-in speed or even minimum idling speed which is about 700 generator speed and 350 engine speed, the circuit of the solenoid and of the motor at will have been interrupted.

If the generator were not separately-excited below the generator cut-in speed, 1000 R. P. M., for example, the voltage generated would be that represented by the curve A-C-B which drops off rapidly to a low value as generator speed decreases. Therefore, it is necessary to provide for separate excitation of the generator, otherwise the relay 3% would close its contacts while the engine is idling, thereby making it possible to operate the starter by closing the starter switch 25 while the engine is in operation. Even with a relatively weak battery supplying the separately-excited field at 3 volts for example, the relay 30 would remain open at idling speed because the voltage then would be about 2.7 volts.

Coil 56 of cutout relay 59 is in circuit with coil 51 of the relay and coil 61 of the current regulator (it and terminal l2. When the generator attains speed of about 1000 R. P. M., the excitation of the coil 56 is sufilcient to cause the attraction of armature 5! of the cutout relay to close its contacts 53 and s4, thereby causing cur rent to flow from the generator to terminal [2, coil 6! of current regulator '60 and coil 51 of relay 50. Relay remains closed until generator voltage falls sufficiently below battery voltage to cause reversal current in coil 51 to buck the magnetism produced by coil 56 whereupon the relay 59 opens to prevent discharge of the battery.

While relay 50 is closed, the generator voltage for various speeds above 100 R. P. M. is indicated by the line B-D-E. The maximum voltage, represented by line D--E, is limited by the voltage regulator Hl which operates in the usual manner to separate contact 18 from contact 11, thereby causing the reduction of field excitation by resistances l5 and M. The regulator will maintain the voltage between 7.2 and 7.8, for example, when cold and between 7.2 and 7.6 when hot. Current output is limited by current regulator 68 which, on exceeding a predetermined current flow through its winding 6i, causes contact to separate from contact 66 whereby resistance 14 becomes effective to reduce field excitation.

In the form shown in Fig. 2, the circuit between 'thebattery wire I]. and thewiresfi includesparalwith blade 2,6 of relay 3.0. The, closing of "i nition. switch I8 and starter switch 25 causes current to flow from the. battery to the coil 94 of relay .90 and coil 3.: of relay 3.0; but, during cranking, the contacts 21 and 215' of relay 30 remain closed while contacts 93 and 95 of relay 90 are closed.

In addition to causing the solenoid 35 to complete the starting motor circuit, the closing of contacts 93 and energizes coil N! of relay I00, causing contacts I03 and I05 to close. The starting motor load on the battery and the rising generator output reduces voltage sufliciently to release the contacts of relay 90 almost immediately, the circuit being maintained through contacts I03 and I 05 which will remain closed until the contacts 21- and are opened. Once released, relay I00 cannot be energized until the contacts of relay 90 are closed. Relay 90 will not close until engine rotation has practically stopped. Therefore, if the engine makes a false start due to misfire or other causes, the relay 30 is thereby opened, the solenoid cannot be reenergized until the engine approaches standstill and the voltage between battery and the generator armature becomes suflicient to operate relay 90. When a normal start is made, relay 30 opens, deenergizing coil I01, and relay I00 opens, causing cranking to cease. At generator cut-in, the generator armature is connected to the battery in the regulator I5 and the closing the star ing switch 25 short-circuits the coil I of relay 90 preventing contacts 03 and 95 from closing. In case the engine has been running and coasts down, the engine starter cannot be operated by pressing the button 25 because battery excitation of coil 3I, acting cumulatively with generator excitation, would cause relay to open its contacts so that coil I M of relay I00 would not be excited. Coil 9I of relay 90 would not be excited because excitation of coil 9| by the battery would be bucked by excitation produced by the generator when separately excited.

Relay 30 is known as a high relay because it operates at relatively high voltage differential between the generator armature terminal and ground. 'It opens its contacts when the voltage of the generator (self-excited) is slightly above that attained at maximum cranking speed. It closes its contacts at a much lower voltage attained at a very low generator speed at which the corresponding engine speed is below that which will sustain engine operation.

Relay 00 of Fig. 2 is known as a low relay because it operates at a relatively low voltage differential between the generator armature terminal and ground. It is adjusted to close at noload battery voltage or slightly less and to release when battery voltage falls, due to loading of the battery when the starting motor at receives current from the battery.

Relay I00 of Fig. 2 is known as the hold-in relay. The closing ofrelay 90 causes coil I 0i of relay I00 to be energized. The closing of contacts I03, I05 of relay I00 causes coil IOI to remain energized although the contacts 33, 95 of relay 90 may open. However, once the hclddn relay I 00 opens, it cannot be reenergized until battery voltage exceeds generator voltage by an amount sufficient to cause the low relay cc to close its contacts.

The control circuit or Fig. 2 prevents, on false starts, the starting motor pinion from crashing into mesh with the engine flywheel gear when the engine falters. In a false start, the engine usually fires once or more, opening the high relay switch 30, then stops, due to misfire or something else. It is possible that such switch might close at this time and a cycle be started where the pinion was forced to engage and disengage rapidly until the engine became selfoperative. However, experience shows that when the switch .30 has once opened, it will remain open until rotation of the flywheel has ceased.

This application is a division of Serial No. 706,618, filed October 30, 1946, now Patent No. 2,572,39 granted October 23, 1951.

. While. the embodiments of the present inven tion as herein disclosed, constitute preferred forms, it is to be understood that other forms might be adopted.

What is claimed is as follows:

1. An engine starter control system comprisins a generator having a field winding, a. storage. battery charged by the generator, an engine starter including an electric motor operated by battery current, a normally open switch for connecting the battery with the motor, an electromagnet for closing said switch, a switch for connecting the generator field winding with the battery in order that the generator will be initially separately excited, a cutout relay for connecting the generator with the battery when generator voltage attains a certain value whereby the generator becomes self-exciting at cut-in speed, said relay disconnecting the generator from the battery when the generator voltage falls below battery voltage in consequence of which the generator returns to separately excited status, and means for controlling the connection between the battery and said electromagnet and including two relay switches having switchclosing electromagnets and having their contacts connected in parallel, the closing of either of these relay switches causing energization of the first mentioned electromagnet, one of the relays being a low (voltage differential) relay which closes contact on no-load battery voltage and opens contact when the battery is supplying current to the starting motor, the other of said relays being a hold-in relay whose electromagnet is initially energized by closing of the contacts of the low relay, energization of the electromagnet of the hold-in relay being maintained by the closing of the hold-in relay, a high (voltage differential) relay having normally closed contacts which control the circuit of the electromagnet of the "hold-in relay, said high relay having an electromagnet sensitive to the voltage of the generator when separately excited, said high relay being so constructed as to remain closed at a generator speed corresponding to maximum cranking speed and to open above maximum cranking speed and below cut-in speed and to reclose at a speed substantially below engine minimum idling speed, and including a normally open, manually closed switch for connecting the battery with the electromagnet of the low relay.

2. An engine starter control system comprising a generator having a field winding, a storage battery charged by the generator, an engine starter including an electric motor operated by battery current, a normally open switch for connecting the battery with the motor, an electromagnet for closing said switch, a switch for connecting the generator field winding with the battery in order that the generator will be initially separately excited, at cutout relay for connecting the generator with the battery when generator voltage attains a certain value whereby the generator becomes self-exciting at cut-in speed, said relay disconnecting the generator from the battery when generator voltage falls below battery voltage in consequence of which the generator returns to separately excited status, and means for controlling the connection between the battery and said electromagnet and including two relay switches having switch-closing electromagnets and having their contacts connected in parallel, a series circuit including the battery, said contacts of the two relay switches in parallel, a normally open, manually closed switch and the normally closed contacts of a third relay switch having an electromagnet sensitive to the voltage of the generator when separately excited, said third relay being a high (voltage differential) relay so constructed as to remain closed at a generator speed corresponding to maximum cranking speed and to open above maximum cranking speed and below cut-in speed and to reclose at a speed sub stantially below engine minimum idling speed,

one of the relays first mentioned being a low (voltage differential) relay which closes contact on no-load battery voltage and opens contact when the battery is supplying current to the starting motor, the other of said relays being a hold-in relay whose electromagnet is initially energized by closing of the contacts of the low relay, energization of the electromagnet of the hold-in relay being maintained by the closing of the hold-in relay.

BROOKS H. SHORT.

JOHN W. DYER.

References Cited in the file of this patent UNITED STATES PATENTS Number Name Date 1,565,854 Hasselbring, Jr. Dec. 15, 1925 1,606,532 Hasselbring, Jr. Nov. 9, 1926 1,531,7 1? Maby June 7, 1927 2 14 Spivey Oct. 20, 1931 1,941,433 Doman Dec. 26, 1933 2,131,026 Doman Sept. 2'7, 1938 2,131,403 Loehr et a1. Sept. 27, 1938 2,572,397

Short et al. Oct. 23, 1951 

